Key to Elachistidae Groups F&G - Forewing dark with pale costal and tornal spots not involving bases of tornal or apical cilia and with other pale markings |
These all need genital dissection for confident identification. The external features listed below may help to limit the number of possibilities, however determination of a metallic sheen to the pale markings is not often easy.
External characters (based on key in MBGBI3) |
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Pale markings of forewing with a metallic sheen (See below) |
Elachista apicipunctella/gleichenella/regificella/geminatella/tengstromi Stephensia brunnichella |
Frons white to yellowish |
Elachista albifrontella/luticomella/alpinella/eskoi |
Frons dark |
Elachista bedellella/kilmunella/littoricola/atricomella/poae/pomerana/canapennella/ orstadii/subnigrella/humilis |
Pale markings of forewing with a metallic sheen |
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Antenna with broad white band at 2/3 |
Stephensia brunnichella |
Median fascia extends halfway across forewing from dorsum |
E.regificella/geminatella/tengstromi |
Median fascia complete, head white |
E.apicipunctella |
Median fascia complete, head metallic grey |
E.gleichenella |
Male genitalia* |
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Uncus rounded, unlobed |
Valva with distinct cucullus |
E.gleichenella |
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Uncus narrower than tegumen |
E.regificella (?E.geminatella/tengstromi) |
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Vinculum broadly rounded |
Juxta with a pair of elongate lobes |
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Juxta without lobes |
E.littoricola |
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Apex of aedeagus with a deep asymmetric cleft. Cornuti absent |
Apex of valva with a small spur |
Saccus short |
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Apex of aedeagus notched |
1 large, 1 small cornuti |
E.atricomella (1) |
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Uncus lobes separated by a 'U'-shaped notch ** |
Apex of aedeagus pointed |
No cornuti |
E.apicipunctella (2) |
Apex of aedeagus square |
2-3 cornuti, 1 bifid |
E.alpinella (3) |
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2 robust, straight, unequal cornuti |
E.canapennella (4) |
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2 medium, curved, equal cornuti |
E.eskoi (5) |
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1 or 2 small cornuti |
E.kilmunella (6) |
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Apex of aedeagus notched |
2 medium, curved, equal cornuti |
E.pomerana (7) |
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1 or 2 small cornuti |
E.humilis (8) |
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Uncus lobes separated by a 'V'-shaped notch ** |
Valval costa ends in a hump at ¾ |
Apex of aedeagus square. 1 small cornutus |
E.albifrontella (9) |
Apex of aedeagus notched. No cornuti |
E.orstadii (10) |
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Valval costa without a hump |
Aedeagus with a subapical swelling and notched apex |
E.subnigrella (11) |
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Apex of aedeagus rounded. 1 medium cornutus. |
E.luticomella (12) |
* Provisional key based on drawings in MBGBI3 and images available at Moth Dissection
The aedeagus of Elachistidae is a very small structure, the shape of the apex can be difficult to determine with certainty and the aedeagus may need to be rotated through its long axis to reveal an apical notch or to be sure there is not an apical notch. Small aedeagal thorns are pretty much invisible without high magnification.
** Measured at the level of the broadest part of the uncus lobes with the uncus lobes set flat. A 'U'-shaped notch is broader than an uncus lobe; a 'V'-shaped notch is narrower than an uncus lobe. Although this feature is not difficult to perceive microscopically it is difficult to photograph as the uncus lobes naturally want to sit in a more angular antero-posterior plane. E.atricomella is intermediate and is keyed out on aedeagal features before this couplet.
The aedeagus of Elachistidae is a very small structure, the shape of the apex can be difficult to determine with certainty and the aedeagus may need to be rotated through its long axis to reveal an apical notch or to be sure there is not an apical notch. Small aedeagal thorns are pretty much invisible without high magnification.
** Measured at the level of the broadest part of the uncus lobes with the uncus lobes set flat. A 'U'-shaped notch is broader than an uncus lobe; a 'V'-shaped notch is narrower than an uncus lobe. Although this feature is not difficult to perceive microscopically it is difficult to photograph as the uncus lobes naturally want to sit in a more angular antero-posterior plane. E.atricomella is intermediate and is keyed out on aedeagal features before this couplet.
(1) E.atricomela: head dark, median fascia interrupted
(2) E.apicipunctella: head shiny white (3) E.alpinella: median fascia indistinct or absent (4) E.canapennella: ws 8-10mm, frons dark, median fascia indistinct or absent (5) E.eskoi: ws 11-14mm, frons dark, median fascia not reaching costa (6) E.kilmunella: ws 9-11mm, frons dark, median fascia complete |
(7) E.pomerana: ws 8-10mm, frons dark, median fascia angulate
(8) E.humilis: ws 9-10mm, frons dark, median fascia indistinct or absent (9) E.albifrontella: head white, median fascia oblique (10) E.orstadii: frons dark, median fascia usually indistinct or absent (11) E.subnigrella: ws 7-8mm, frons dark, median fascia indistinct or absent (12) E.luticomella: head yellowish, median fascia at 90deg to costa |